Welcome to the forums lostriots
and you are right you will need to upgrade all of that
also you will need to upgrade your powersupply so your hardware doesnt fail
ocz is good but i always go with corsair( you can go to their website, input your motherboard, and they will give you compadible RAM for it)
processor choice is good, to save money go with 3800 becuase you wont see much difference between the 2.
that should help you with your video card choice^
as far as nvidia vs ati we arent going to argue about it because its a matter of opinion and the conversations will get HEATED. i personally like nvidia better but ati has amazing cards too.
good luck with your computer and feel free to ask questions